An efficient asymmetric synthesis of nitroolefinic lactones with chiral nitroenamines possessing bulky chiral leaving groups
作者:Xiaowu Yang、Rui Wang
DOI:10.1016/s0957-4166(97)00452-7
日期:1997.10
An efficient asymmetric nitroolefination of enolates 4a-c, 5 afforded multifunctional group nitroolefinic lactones 7a-e and 8a,b containing stereogenic quaternary carbon centers using bulky chiral nitroenamines 1a,b–3a,b as chiral auxiliaries. Studies on the effect of the bulkiness of leaving group showed that bulky nitroenamines 1a,b gave higher ees and yields than those of the less bulky 2a,b–3a
有效的烯醇盐4a-c,5的不对称硝基烯烃化反应,使用了庞大的手性亚硝胺1a,b-3a,b作为手性助剂,从而得到了多官能团的硝基烯烃内酯7a-e和8a,b,其中含有立体生成的季碳中心。研究的离去基团的体积的效果表明,笨重nitroenamines 1A,B,得到更高EES和产量比那些不太笨重的图2a,2b-3A,3B。提出了一种可能的循环跃迁模型,以阐明S的选择性。